Combined Historical Scenario - a giant mod combining several earlier mods and a lot of new stuff, in order to make WitP more historicaly accurate. Many more ship classes, more locations, air forces on squadron level, LCUs revamped etc. etc. - it's great! Get it at Spooky's
Plus cool new, more accurate map and (imo) better graphics for ships and planes. (the plane tops in this thread, by The Elf, are sized proportionately. The map and the plane tops are probably two of the top 3 things with CHS.
The older I get, the better I was.